Study on the shear performance of novel ring-grooved group-rivet connectors

Owing to their excellent shear performance and unique installation and removal process, the novel ring-grooved rivets present themselves as a promising alternative to welded studs and high-strength bolts. However, the shear mechanisms of rivet groups, including shear non-uniformity and reduction coefficient, need to be clarified. To address this, five groups of group-rivet shear specimens were designed and tested using a single-sided push-out device. The effects of rivet diameter, spacing, and rows and columns of rivet array on the shear capacity, stiffness, load-slip behavior, and strain behavior of group-rivet shear connectors were systematically investigated. In addition, a refined numerical model was developed to explore the shear transfer mechanism and parametric effects. Based on the analysis of group-rivet effects, shear capacity prediction models were proposed for two failure modes. Experimental results reveal that group-rivet shear connectors mainly exhibit two failure modes: rivet shear failure and UHPC splitting failure. The load-slip curve exhibits five distinct stages: frictional bearing, frictional slipping, elastic bearing, elastoplastic behavior, and post-peak softening. As rivet array increases, the slip plateau resulting from the 2 mm assembly hole tolerance disappears. With the increase of the shear area of the rivets, the bearing capacity and stiffness increase, but the ultimate average shear stress decreases significantly. Numerical results reveal that the rivet spacing (3d to 7d) and the height-to-diameter ratio (3.2–5.6) of the embedded section have a limited influence on shear performance, with the shear capacity variation remaining within 10 %. In contrast, the rivet diameter and the number of rows and columns significantly influence shear non-uniformity, with the effect intensifying as these parameters increase. The shear force distribution along the row direction is more uneven than that along the column direction. Specifically, the front-row rivets bear the highest shear force, followed by those in the rear, while the middle rivets experience the least. From numerical parametric studies, it is recommended that the minimum spacing between ring-grooved rivets in group connections be no less than 6d, and the height-to-diameter ratio of the embedded segment should be no less than 3.5. The shear capacity calculation methods proposed in this study showed relative errors within 10 % between theoretical predictions and experimental results. The findings of this study provide reference for the design and engineering application of ring-grooved rivet shear connectors. • A novel ring-groove riveted shear connector for steel-UHPC composite beams has been developed. • A single-sided shear testing apparatus was designed to investigate the shear performance of group-rivet connectors. • A refined numerical model of group-rivet shear connectors was established for shearmechanism and parametric effects analysis. • The shear mechanisms of rivet groups, including shear non-uniformity and reduction coefficient, has be clarified. • The shearing capacity calculation methods for the modes of rivet shear and pull-out failure were developed.